• 제목/요약/키워드: Potential well structure

검색결과 538건 처리시간 0.023초

SCBF 장치에서 이온전류에 대한 포텐셜 우물 구조의 영향 (Effect of Potential Well Structure on Ion Current in SCBF Device)

  • 주흥진;박정호;고광철
    • 한국전기전자재료학회논문지
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    • 제20권5호
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    • pp.471-477
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    • 2007
  • SCBF(Spherically Convergent Beam Fusion) device has been studied as a neutron source. Neutron production rate is a most important factor for the application of SCBF device and is proportional to the square of the ion current[1]. It is regarded generally that some correlations between the potential well structure and the ion current exist. In this paper, the ion current and potential distribution were calculated in a variety of grid cathode geometries using FEM-FCT method. Single potential well structure was certified inside the grid cathode. The deeper the potential well became, the higher the ion current due to the high electric field near the grid cathode became.

GaN LED에서 tunneling과 piezoelectric potential에 의한 carrier lifetime 연구 (Carrier lifetime study in GaN-based LEDs: the influence of tunneling and piezoelectric potential)

  • 조영달;오은순;김대식
    • 한국광학회:학술대회논문집
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    • 한국광학회 2001년도 제12회 정기총회 및 01년도 동계학술발표회
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    • pp.48-49
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    • 2001
  • GaN는 wurzite structure를 갖는 wide bandgap III-V족 반도체로서, 청색 반도체 laser diode (LD), light emitting diode (LED)등으로 응용되는 물질이다. InGaN quantum well은 GaN계의 청색 LD, LED 구조에서 활성층으로 사용되기 때문에 이에 대한 광학적 연구가 활발하다. InGaN는 GaN위에 성장하면 strain에 의해 piezoelectric 효과가 크게 나타나는 것으로 알려져 있다. 이러한 piezoelectric potential에 의해 외부에서 voltage가 가해지지 않은 상황에서도 InGaN quantum well내의 electron, hole의 wave function이 비대칭 potential의 영향을 받게된다. (중략)

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희생양극식 음극방식이 적용된 해안 교량 구조물의 방식거동 (Cathodic Protection Behavior of Coastal Bridge Structure with Sacrificial Anode Cathodic Protection System)

  • 하지명;진충국;정진아
    • Corrosion Science and Technology
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    • 제11권6호
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    • pp.242-246
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    • 2012
  • This measurement represents the effectiveness of sacrificial anode cathodic protection (SACP) system in a coastal bridge structure. To verify the cathodic protection (CP) effect, the monitoring sensor (DMS-100) that could measure potential, corrosion rate, current, concrete resistivity, and temperature was embedded. The measurement conducted for three years after CP system was installed. Specifically, due to the fact that fresh water and sea water was repeated in the bridge structure, this bridge structure presented special CP behavior. Measurement factors were CP potential, CP current, concrete resistivity, and depolarization potential. In addition, visual inspection was also carried out. As a result of current and depolarization measurement, CP system was well activated in most piers.

Design optimization of GaN diode with p-GaN multi-well structure for high-efficiency betavoltaic cell

  • Yoon, Young Jun;Lee, Jae Sang;Kang, In Man;Lee, Jung-Hee;Kim, Dong-Seok
    • Nuclear Engineering and Technology
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    • 제53권4호
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    • pp.1284-1288
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    • 2021
  • In this work, we propose and design a GaN-based diode with a p-doped GaN (p-GaN) multi-well structure for high efficiency betavoltaic (BV) cells. The short-circuit current density (JSC) and opencircuit voltage (VOC) of the devices were investigated with variations of parameters such as the doping concentration, height, width of the p-GaN well region, well-to-well gap, and number of well regions. The JSC of the device was significantly improved by a wider depletion area, which was obtained by applying the multi-well structure. The optimized device achieved a higher output power density by 8.6% than that of the conventional diode due to the enhancement of JSC. The proposed device structure showed a high potential for a high efficiency BV cell candidate.

나노파이버 기반의 의료용 지지체 제작 기술 및 응용 (Fabrication of Nanfiber-based Medical scaffolds and their Prospective Application)

  • 신호준;이창훈;조인희;김인애;이용재;박기동;신정욱
    • 한국공작기계학회:학술대회논문집
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    • 한국공작기계학회 2004년도 춘계학술대회 논문집
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    • pp.518-523
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    • 2004
  • PLGA was suggested. Under various conditions, their diameters and porosity as well as mechanical strength were evaluated. In addition to those, cell(chondrocyte) proliferation and formation of extracelluar matrices were also investigated along with the conventional membrane type PLGA scaffolds for the potential use in tissue engineering. As conclusions, this type of scaffold showed a potential of application to tissue engineering in view of mechanical stability as well as cellular responses.

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지반-구조물 상호작용을 고려한 원통형 유체저장탱크의 지진해석 (Earthquake Analaysis of Cylindrical Liquid Storage tanks Considering Effects of Soil-Structure Interaction)

  • 김재민
    • 한국지진공학회:학술대회논문집
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    • 한국지진공학회 1999년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall
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    • pp.83-90
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    • 1999
  • This paper presents a method of seismic analysis for a cylindrical liquid storage structure on horizontally layered half-space considering the effects of the interior fluid and exterior soil medium in the frequency domain. the horizontal and rocking motions of the structures are included in this study. The fluid motion is expressed in terms of analytical velocity potential function which can be obtained by solving the boundary value problem including the sloshing behavior of the fluid as well as deformed configuration of the structure. The effect of the fluid is included in the equation of motion as the impulsive added mass and a frequency-dependent convective added mass along the nodes on the wetted boundary with structure. The soil medium is presented using the 3-D axisymmetric finite elements and dynamic infinite elements. The present method can be applied to the structures embedded in ground as well as on ground since it models the soil medium directly as well as the structure. For the purpose of vertification dynamci characteristics of a tank on homogeneous half-space is analyzed. Comparison of the present results with those by others shows good agreement.

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더블 게이트 구조 적용에 따른 IGZO TFT 특성 분석 (Analysis of the Output Characteristics of IGZO TFT with Double Gate Structure)

  • 김지원;박기찬;김용상;전재홍
    • 한국전기전자재료학회논문지
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    • 제33권4호
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    • pp.281-285
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    • 2020
  • Oxide semiconductor devices have become increasingly important because of their high mobility and good uniformity. The channel length of oxide semiconductor thin film transistors (TFTs) also shrinks as the display resolution increases. It is well known that reducing the channel length of a TFT is detrimental to the current saturation because of drain-induced barrier lowering, as well as the movement of the pinch-off point. In an organic light-emitting diode (OLED), the lack of current saturation in the driving TFT creates a major problem in the control of OLED current. To obtain improved current saturation in short channels, we fabricated indium gallium zinc oxide (IGZO) TFTs with single gate and double gate structures, and evaluated the electrical characteristics of both devices. For the double gate structure, we connected the bottom gate electrode to the source electrode, so that the electric potential of the bottom gate was fixed to that of the source. We denote the double gate structure with the bottom gate fixed at the source potential as the BGFP (bottom gate with fixed potential) structure. For the BGFP TFT, the current saturation, as determined by the output characteristics, is better than that of the conventional single gate TFT. This is because the change in the source side potential barrier by the drain field has been suppressed.

Hydroelastic vibration analysis of wetted thin-walled structures by coupled FE-BE-Procedure

  • Rohr, Udo;Moller, Peter
    • Structural Engineering and Mechanics
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    • 제12권1호
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    • pp.101-118
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    • 2001
  • The reliable prediction of elastic vibrations of wetted complex structures, as ships, tanks, offshore structures, propulsion components etc. represent a theoretical and numerical demanding task due to fluid-structure interaction. The paper presented is addressed to the vibration analysis by a combined FE-BE-procedure based on the added mass concept utilizing a direct boundary integral formulation of the potential fluid problem in interior and exterior domains. The discretization is realized by boundary element collocation method using conventional as well as infinite boundary element formulation with analytical integration scheme. Particular attention is devoted to modelling of interior problems with both several separate or communicating fluid domains as well as thin-walled structures wetted on both sides. To deal with this specific kind of interaction problems so-called "virtual" boundary elements in areas of cut outs are placed to satisfy the kinematical conditions in partial connected fluid domains existing in realistic tank systems. Numerical results of various theoretical and practical examples demonstrate the performance of the BE-methodology presented.

구형 집속 빔 핵융합 장치에서 그리드 음극 구조의 최적 설계 (Optimal Design of Grid Cathode Structure in Spherically Convergent Beam Fusion Device)

  • 주흥진;박정호;황휘동;최승길;고광철
    • 한국전기전자재료학회논문지
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    • 제21권4호
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    • pp.381-387
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    • 2008
  • Neutron production rate in spherically convergent beam fusion(SCBF) device as a portable neutron source strongly depends on the ion current and the grid cathode structure. In this paper, as the process of design and analysis, Design of Experiment(DOE) based on the results by Finite Element Method-Flux Corrected Transport(FEM-FCT) method is employed to calculate the ion current. This method is very useful to find optimal design conditions in a short time. Number of rings, radius of rings, and distance between the grid cathode and center are selected as control factors. From the results in the optimized model, the higher ion current is calculated and deeper potential well is also observed.

해양구조물용 RE36강 용접부의 부식거동 및 기계적 특성에 미치는 용접후 열처리 효과에 관한 연구 (A Study on the Post-Weld Heat Treatment Effect Affecting Corrosion Behavior and Mechanical Property of Welding Part of RE36 Steel for Marine Structure)

  • 김성종;문경만
    • Journal of Welding and Joining
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    • 제19권1호
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    • pp.65-74
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    • 2001
  • A study on the corrosion behavior in case of As-welded and PWHT temperature 55$0^{\circ}C$ of welding part of RE36 steel for marine structure was investigated with parameters such as micro-Vickers hardness, corrosion potential measurement of weld metal(WM), base metal(BM) and heat affected zone(HAZ), both Al anode generating current and Al anode weight loss quantity under sacrificial anode cathodic protection conditions. And also we carried out slow strain rate test(SSRT) in order to research both limiting cathodic polarization potential for hydrogen embrittlement and optimum cathodic protection potential as well as mechanical properties by post-weld heat treatment(PWHT) effect. Hardness of HAZ was the highest among three parts(WM, BM and HAZ) and the highest galvanic corrosion susceptibility was HAZ. And the optimum cathodic polarization potential showing the best mechanical properties by SSRT method was from -770mV to -875mV(SCE). In analysis of SEM fractography, applied cathodic potential from -770mV to -875mV(SCE) it appeared dimple pattern with ductile fracture while it showed transgranular pattern (Q. C : quasicleavage) under -900mV(SCE). However it is suggested that limiting cathodic polarization potential indicating hydrogen embrittlement was under -900mV(SCE).

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